<?php

session_start();

//initialising variables

$username = "";
$email = "";
$errors = array();

//connect to db

$db = mysqli_connect('localhost','root','','practice') or die("couldn't connect to the db");

//Register users

if (isset($_POST['reg_user'])) {

// Receive all input values from the form

$username = mysqli_real_escape_string($db, $_POST['username']);
$email = mysqli_real_escape_string($db, $_POST['email']);
$password_a = mysqli_real_escape_string($db, $_POST['password_a']);
$password_b = mysqli_real_escape_string($db, $_POST['password_b']);

//form validation : ensure that the form is correctly filled...
// by adding (array_push()) corresponding error onto $errors array

if(empty($username))
 {
     array_push($errors, "username is required!");
 }
if(empty($email))
 {
     array_push($errors, "email is required!");
 }
if(empty($password_a))
 {
     array_push($errors, "password is required!");
 }
if($password_a != $password_b)
 {
     array_push($errors, "Password don't match!");
 }

// first check the database to make sure
// a user does not already exits with the same username and/or email

$user_check_query = "SELECT * FROM user WHERE username = `$username` or email = `$email` LIMIT 1";

$result = mysqli_query($db, $user_check_query);
$user = mysqli_fetch_assoc($result);

if($user) {       // if user exist
    if($user['username'] === $username)
     {
         array_push($errors, "Username already exists");
     }
    if($user['email'] === $email)
     {
         array_push($errors, "Email already exists");
     }
}

// Finally, Register the user if there is no error in the form

if(count($errors) == 0 ){

     $password = md5($password_a);   // Encrypt the password before saving in the database
     $query = "INSERT INTO user (username, email, password) VALUES ('$username','$email','$password')";

     mysqli_query($db,$query);

     $_SESSION['username'] = $username;
     $_SESSION['success'] = "You are now logged in";

 }
 header("location: index.php);

}

?>